Single sheet feeders



Jan. 19, 1960 J. c. LAWRENCE SINGLE SHEET FEEDERS '7 Sheets-Sheet 1 Filed Feb. 16, 1955 l e E m m I uw .l N i www. Q, NW #M 9+ MM. QN o .ww NM www MN mw Si M ww ww l. l wm Q M h NN Q N Jan. 19, 1960 J. c. LAWRENCE 2,921,788

SINGLE SHEET FEEDERS Filed Feb. 1e, 1955 'r sheets-sheet 2 BY l, m 56 57 56 5 637'" 1 Jan. 19, 1960 .1. c. LAWRENCE '2,921,788

SINGLE SHEET EEEDERS Filed Feb. 16, 1955 7 Sheets-Sheet 3 y? l INVENTOR.

Jan. 19, 1960 J. c. LAWRENCE 2,921,788

SINGLE SHEET FEEDERS Filed Feb. 16, 1955 7 SheebS-Sleet 4 54 5 57 INVENToR. L JAMES C. LAM/@ENCE yl 58 @Mz-cam ATTORNEYS Jan. 19, 1960 v .1. c. LAWRENCE 2,921,788

SINGLE SHEET FEEDERs Filed Feb. 16, 1955 7 Sheets-Sheet 5 57 5 7 54 INVENTOR.

Jan- 19, 1960 .1. c. LAWRENCE 2,921,788

SINGLE SHEET FEEDERS Filed Feb. 16, 1955 '7 Sheets-Sheet 6 Jan. 19, 1960 J. c. LAWRENCE 2,921,788

SINGLE SHEET FEEDERS Filed Feb. 16, 1955 7 Sheets-Sheet 'Z' INVENToR. /49 :f4/155 c. An/@m05 /5/ M @www M 2,

United States Patent() ice SINGLE SHEET FEEDRS James' CILawrence, Seattle, Wash.

Application February 16, 1955, Serial No. 488,643

8 Claims. (Cl. 271-34) The present invention relates to a feeder for feeding to a machine, such as a sander, for example, single-sheets, such as of plywood, from a stack.

In general, the `purpose of .the feeder is to, receive la stack of closely piled sheets `andffautomatically to feed these sheets edgewise, one at a time, from the top of the stack. An object of the invention is to provide `such a sheet feeder which can handle large sheets of-material, such as four feet by eight feet, and which can be adjusted readily to feed sheets of different Width andlength.

Another object is to provide a sheet feeder'of automatic character which will receive a stack of sheets-from a conveyor when the feeder isy empty and k'lift such-.sheet stack until the upper sheet reaches a feeding station. at a predetermined elevation, whereupon `single `sheets 4fare fed edgewise from the top ofthe stack insequence, Vand the stack of sheets is raised automatically, the thickness of one sheet between each sheet feeding operation, until all the sheets of the stack have been fed. When the feeder has thus been emptied, it will receive automaticallyanother stack of sheets, and the sheets of this stack will be fed similarly in sequence. Y d .3

A particular object of the invention is to position each sheet accurately before it -is fed edgewise from the stack, so that it will be aligned precisely in predeterminedv position before being fed, and thence will be moved kalong a true path into the-machine. An 1associated.object is to An additional object is to provide suitable controls for Y such a sheet feeder so that -the feeder may be` stopped and started at the will of the operator, its'speed of feed may be regulated, yand the type of sheet feeding operation may be selected so that alternate sheets willbe oifset to opposite sides of a central position, asdiscussed above, or all the sheets will be fed from/a central position, as may be desired.

The sheet feeder includes an elevator Vonto which a stack of sheets to Vbe .fed is delivered, and when inplace upon the elevator it is automatically hoisted. Whend'he top of the stack carried by the elevator reaches feeding elevation, the elevator movement automatically is stopped and automatically reciprocable squaring armsare moved to engage the top sheet edgewise and shift it transversely of the feeding direction as may beanecessary to square the sheet with Vthe feeding direction. Sheet feeding means then slide the sheet lengthwise from the top of the stack. As soon as this sheet has been.moved.substantiallyolf the stack, upward movement Yof the elevator fis initiated again to raise the stack a distance equal to the thickness of the sheet thus fed. Thereupon the squaring arms are reciprocated Tto square the new top sheet, and .it in `turn is slid oif the top of the stack by the sheet feeding means.

'.otheristae'k of sheets.

2,9Zl,'?88 latented Jan. 19, 1960 yWhen all the sheets in thestack havethus been fed, the empty elevator automatically is lowered to receive angparts broken away.

Figure 2 is a transverse sectional View through a portion of the sheet'feeder taken on line 22 of Figure 17, and Figure 3 is a similar view showing parts in a diferent operativeposition.

`.Figure 4 is a detail longitudinal sectional View through Van operating cylinder shown in Figures 2 and 3.

:Figure "5 is 1a detailed bottom perspective view of the `squ'anng arms and their drive mechanism at the right end fofFigures v2 and 3.

` 4'Figures 6 -to 15, inclusiva-are diagrammatic views of .thesquaring'arm drive pistons shown in Various positions.

Figure V16 is a vertical transverse section through the sheet feeder.

Figure1l7 is a side'elevation view of a portion of the upper part 'of lthe sheet feeder, and'Figure 1S is a similar `view with; parts .in :a different operative position.

Figure 19 VisV a vertical sectional view through brake mechanism of the apparatus.

4FigureZO ^is `a diagrammatic perspective view of elevator-drive mechanism and Figure 2l is an enlarged detailfviewof its hydraulic cylinder components.

Figurel is a wiring diagram of the control system.

The general type of operation performed by the apparatus involves receiving Yedgewise a stack of panels 4piled -in face-to-face contact, Velevating such stack of panels until the upper panel has reached a predeterminefg feeding fposition, arresting upward movement of the staczat such location, sliding the uppermost panel edgewise on the top'. of the stack in a feeding operation, raising the stack through a further increment equal to the thickness of the panel discharged, slidinganother panel olf the top of the stack in a feedingoperation, again raising the stack through an increment equal to the thickness of the v*panel discharged, repeating the single panel feeding and .of panels S, the panels of which are to be fed individually,

is moved edgewise into the apparatus preferably on rolls 1 from .a suitable conveyor which is not shown. These rolls Yare vlocated alongside the frame 10 of the apparatus, which -is :of vgenerally rectangularV shape. Within such frameand coplanar with rolls 1 are rolls 11 of another roll set. The rolls 1 and 1,1 are driven all at the same speedby-a motor 12 with a `suitable gear reduction drive, so that Vthe ldrive chain 13 interconnecting the rolls and `powered by the. motor 12 will move rather slowly. The machine frame includes four columns 14 located one at each corner of the lower portion of Vframe 10, and these columns carry 'a superstructure 15 bridging between the columns.

` Within the trarne is received an elevatorincluding two parallel end members 16 and parallel bars k17 interconnecting such cross members 16 and spaced apart distances Vequal to the spacing of rolls 11 so that when the elevator platform is in its lower position thebars 17 are located in alternate arrangement with the rolls 11. Elevatorhoisting chains 2 in housings 20, one at each corner ofgthe frame alongside a column 14, are connected -to the ends of the elevator platform bars `16 forming the corners of such platform. The'hoisting chains 2 are ment of such a pusher bar with an Yedge of a panel, theredrivel! by Chain and Sprocket mechanism Within 110115- Y fore, means are provided for squaring the position of the ings 21 at one side of the frame, and one of these chain Y' drives in turn is driven by reversing gearing in housing 22. Movementof the hoisting chains 2 at one side of the frame is transmitted to the hoisting chains 2 at the other side of the frame by shafts 23 interconneting'the Yupper`drive sprockets of these chains at opposite sides of the frame.

The drive for t-he hoisting mechanism in housings 1.1V

connected lto chains 2 must, of course, be reversible, and

' the vertical movement of chains 2 required is not great.

Consequently, reversible drive of the hoisting chains may zontally in the superstructure 15 of the frame which will VVcoordinate the Vdrive at opposite ends of the'elevator.

Conveniently the reciprocating member may be an elongated cylinder`24 guided by and movable relative to a stationary piston on a rod 25 shown in Figure 21. Chains 28 may be secured to the opposite ends of this cylinder,

chain drive at the opposite ends of the superstructure. so that, as the cylinder 24 reciprocates, the shafts 23 Ywill `be rotated to move the chains 2. Reciprocation of such cy1inder'24 on rod 25 is effected by supplying fluid unf der pressure, such as oil, through the connection 26 to the left end'of the cylinder 24,'as seen in Figure 1,'forA ends of arms 30 are interconnected by and carry barsv 31 disposed in parallel arrangement, as shown best in Figures 2 and 3, on which the various components of the feeding mechanism are mounted. These bars will be elevated bodily and will move endwise slightly as the arms`30 swing about the axes of shafts 3., j

In"opposite ends of the bars 31V are mounted axles 32 carrying sprockets 33 aboutwhich extend two endless chains 34 arranged in parallel vertical planes.- These r chains are interconnected by sheet feeding pusher bars 35 shown best in Figures 2, 3, 16, 17 and 18. IheseV chains extend lengthwiserof the feeder frame a distance greater than the length of the longest panel to be fed by thc-.ap-V

paratus, and in order to reduce'as Yfar as possible the dwell between the feeding ofsuccessive panels, it Vis preferredrthat two of such bars 35 be provided; f

beY effected conveniently by a member reciprocating hori- :to the gearing mechanism 29 in casing 22 and tothe top panel'irrespective of the Vorientation ofthe stack S of panels on the elevator. Such means include pairs of oppositely reciprocable squaring arms shown best in Fig- Yures 2, 3, 5 and l6. Each pair of such arms includes an arm 4 having a blade'40 engageable with one'edge of the top panel on a stack and an opposite arm 41 carrying a blade 42 engageable with the opposite Vedge of the top panel. Y' Y s Drive mechanism'for the squaring arms 4 and 41 effects simultaneous rreciprocatio'n in opposite directions of .both squaring arms in each pair. Such 'drive mechanism includes racks 43 and 44 on the squaring arms 4 and 41, respectively, with which mesh gears 45 and 46, respectively. Rotatably integralwith each gear 45 is a gear 47 and rotatably integral with each gear 46 is a `gear 48. Rotation of gears 45 and'46 will thus be effected by gears 4 7 and 48,'respectively, Vand simultaneous'rotaftion of these gears will eiect simultaneous reciprocation of the squaring arms`4 and 41, because of the engagernient of gears 45 and 46 with the racks 43 and 44. If the gears are rotatedproperly Vrelative to eachother, the 'squaring arms can be thus moved simultaneously toward Yeach other, and 'if the gears are rotated oppositely, the squaring arms'will be moved simultaneously to separate plates v40 'and 42.

-Since, in order to square a panel of any appreciable length, it isdesirabletoengage an edge at a plurality of spaced locations,`th'e drive mechanismvis arranged to move the two squaring arms 4 and the two squaring arms V`41 shown'in Figure 2, for example, simultaneously in the same direction and to the Vsame extent. Actually, it -vvuld be possible to square the position of a panel simply -by engaging one edge with a single 'squaring member and *shifting thefpaneledgewise until its opposite edge en- -gaged xed locating stop means. ParticularlyV for long panels, however, the squaring action can be effected more Y `vaccurately and expeditiously by Vengaging one edge at a plurality of locations.' f

-Also, while as mentioned above a panel` might be located by pushing it edgewise into engagement with i fixed locating stop means, it'is frequently desirable to In order that the feeder may beV suiiiciently4 versatile to be used for feeding machines Voperating at different Y speeds Vit is preferred that a variable speed drive be provided-for the endless chains 34. Conveniently, such a variable speed drive may be elected by an oil motor 36 the Yspeed of which can be varied simply by regulating the Vsupply of oil to the motor.Y This motor, as shown in Figures 2 and 3, will drive chain and sprocket mechanism y37 to turn one ofthe shafts 32 carrying'sprockets 33 with which the chains 34 are engaged. As these chains are driven the bars 35 will always move in the direction from right to left, as seen in Figures l, 2 and 3, when carried by the lower stretches Vof the chains. Since bars 35 will not be thickerthan the thinnest .panel Vto'be fed, such movement will causeV each bardun'ng such travel toslide only a single panel from the top of a stack'on the elevator.

locate onepanelr in oneY edgewise-position for feeding and the next panel in a diicrent edgewise location for feeding. Y Moreover, it is ordinarily desirable to locate panels of differentwidths in diierent positionsV for feedd ing. With the present type of squaring apparatus engageable with opposite edges of-a panel at a plurality of locations, it is possible to locate alternate vpanels in differ ent positions and toaccommodateand feed panels of different widthsV quite readily. In'forder to obtain such an operation, however, itis necessary that all of the squaring arms be driven conjointly and in related fashion. To eiect Vcontrolled reciprocation ofthe squaring arms '4 and 41,- it is only necessaryto coordinate the rotation Lof gears 47 and 48.V f Y As shown in Figures 2 and y5, the gears 47 are driven conjointly because they mesh withjthe racks 5 and 50, respectively, of drive bar 51. Similarly, thek gears 48 mesh respectively with racks 52 and 53 of drive rod 54. Reciprocation of drive rod 51 thuswill effect simultaneous andequal reciprocation of squaring arms 4 in the sarnedirection, and movement of drive rod 54 will eiect simultaneousand equal Vmovement of squaring arms 41 Yin the same direction. Itis therefore only necessary to coordinate the movement of drive rods 5-1` and 54 in order to establish the initial positions and spacing ofthe squaring plates 40 and 42 Vwhen open and their closed positions depending upon the width of the sheet to be squared and the location of such sheet desired relative to the machine to which the sheet is to be fed. Y Y Y Y The mechanism for reciprocating the drive" rods is Yshown best in Figures 2, 3 and 4 as incorporating compostte pistonsV and cylinders. Since the piston and cylinademas der mechanism :is Yth'esame for 'each'ofth'e drive zrods, as shown in Figure 4, only one;o'f'these Y'need be described. Each composite actuator includes an outer cylinder 55 in which a piston'56"re'ciprocates. Thispises jc'anb-e" suppled'to both-'offt'heinner cylinders Sl'and' to .one 'only 'of the 'outer cylinders VS5.` By 'thus regulating the supply ofluid'pressureto the" cylinders and by setting thestop bars. properly panels of any width within plates either so that successive panels of a Ygiven width will be fed along the same path, or along alternately oiset paths, mechanism for adjusting the positions of the stop bars 64 and 65 is provided. Such adjustment conjointly of the positions of both bars lis effected by turning handle 68 to rotate shaft 6, which in turn moves the :stop bars 64 and 65 simultaneously in the same direction and to the same extent. Such stop bars may be held in any adjusted position by providing a spring-pressed pin in the handle of `crank 68, which will engage in any selected hole of the latch plate 69.

ton carries an inner cylinder V57 and has an aperture 5 limits can be.fedfrom"fh'e' top Aofa stack successively through which the drive rod may move. Thedrive rod along a vsingle :predetermined ipath, or panels fed from in turn has on it a smaller piston 58 .which can reciprotheitop of the staclcmayibe moved .alternately along two catein theinner cylinder 57, .'os'et paths. This lattentype 'o'foperation frequently Fluid under pressure, such as air, is supplied to and is desirable whenthe panels are fed .to 'sanding machines exhausted from the outer cylinderSS at one side of the 10 l0 redll the Wear 0111116 SldIlg`I0l1S- FgufCS t0 15, piston 56 through a conduit 55,.and such fluid is supinclusive, illustrate diagrammatically positions of the stop plied to and removed from the outer cylinder at the other 'bars vWhich would 'be established t0 "hand-le feeding 0f side of the piston 56 through a second conduit 55'. Air panels of ditferentwidth's, 'and either 210mg a Single Path or other uid under pressure is supplied to the inner r alternatelyalongolset paths. cylinder 57 at one side of piston S8 by an aperture 57' 15 Assuming that air underpre'ssure Vis supplied to the communicating with a bore in the drive rod and a conduit right ends Of both cylinders 157 vand both cylinders 55 as 57" connected to the bore. Fluid under pressure is supseen in Figures 2 and 3,*the squaring arms would be plied t0 and exhausted from the inner cylinder-.'57 'at "the `i11OVd iIltO and held in the :fully-'extended positions ShOWIl opposite side of piston 58 through an aperture 58', a bore 'in Figure 16. VInV this Aposition it is assumed that the yin the drive rod and a conduit 58" connected to it. `20 'squaring plates 40 and 42 Vare spaced apart sixty inches. It will be appreciated that it would .be very dieult to VBecause the sears 45er@ 'twice as large as the gears 47 Vbalance the pressures in the two cylinders 55 for the two and the gears 46 are twice as'lar'ge as the gears 4S, the drive rods 51 and 54 withprecision, and similarly it squaring arms 4 and 41 will `be moved twice as far as would be difficult to balance -exactly the pressures in the the drive rods 51 and 54. Since it Vs-desired to be able to cylinders 57 for the two drive rods. Such pressures, 25 -feedwith the feeder apparatuspanels from twelve inches therefore, cannot be relied upon to move the drive rods 'in Width t0 fOrty-eight inches .in Width in increments of V51 and 54, and consequently the squaring arms 4 and 41, lone inch, it is appropriate Afor the stroke of the pistons to predetermined sheet locating positions. For that 58 ill CYIldefS 57`0'beuthree inC'heS and the Stroke 0f reason positive stop mechanism cooperating with the the PSODS 56 ill Cylinders '55 t0 be Ilvlle inches drive`rods 51 and 54 and operable to stop them positively 30 A sanding machine, for example, receiving panels from in predetermined operative positions is provided. tht? feeder described, DmuY WOuld be able 0 aC-COITI- The drive rod stop mechanism as best shown in Figure -modate panels forty-eight inches in Width. If narrower includes a shaft 6 carrying pinions 60 and 61 which panelsV are fed, it usually is desired .to offset them rst mesh respectively with the racks 62 and 63 on stop bars in one direction and then -in the other transversely of 64 and 65. These bars are suitably mounted alongside 35 r'illel' lengths, S0 that 011C Cdge 011th@ Diller 0f each Panel the respective paths of reciprocation of drive rods 51 and Will be yaligned with the Vlocation which the edge of a 54, in parallel, and such stop bars have hooked ends 66 forty-eight inch panel would -haveV occupied. Bearing and 67, respectively, which project into thepa'ths ofmovein mind the maximum Width opening of sixty inches of ment of their respective drive rods. When either of the the squaring plates and 42., lthe .strokes of the large drive rods strikes the hook of its ystop bar, the movement 40 PSOBS 55 21S being Bille illChQ he 1S1'0k6S l0f the Small of such drive rod will be interrupted, and the ,squaring pistons 58 relative to the'rcylinders `57 as being three plates 4t) or 42 controlled by such drive rod will be inches,and the movement .of ythe squaring arms 4 and positioned as positively as though such plates constituted 41 being twice as great asfthe Vmovement of the drive stationary locating stop means. When thesquaring plates l'OdS 51 `and 54, the following table 'shows therelationare thus located, they do actually constitute xedrefer- Ship of piston movement to squaring plate positioning ence stop means, and for that particular operation serve Vfor panels of different widths centered or alternately olfthe same function as stationary stop means. set as represented by the illustrations of Figures 16 and 6 In order to accommodate panels of different widths to 15, respectively.

yPanel Large Small Port Large. Small Strbd Stop mh pas par. as: its Inches Inches Inches Inches Inches Inches 0 o 01 0 o so 0 `e 0` 3 6 4s o 6 A3 0 6 4S e 0 12 0 3 6 42 4 0 9 4% Y0 9 42 9 o 1s 0 3 e 36 Centered 6 0 12 6`- `0 12 36 Oliset 18 to Port- 9 3 24 0 3 6 30 Centered... 7% o 15' 7% o i 15 3o Centered--- 9 0 18 :9 0 18 24 Centered--- 90 1% 21 9 j 1% 21 1s and in order to set the stop bars for locating the squaring While the representations of l'Figures 6 to 15 of the positioning of pistons 56 and 58 incylinders 55 and 57 are very diagrammatic, the showing in Figures 2 and 3 is a much more structural representation of the mechanism illustrating the movement of the squaring arms which occurs in positioning for ofset feeding a rpanel thirty-six inches in width and corresponding to the diagrammatic representation of Figure l0. In such offset squaring, as represented by this ligure and by Figures 6, -8 and 12, fluid under pressure is supplied to lthe left end of one of the large ,cylinders and to theright end of the other through connection 55", the opposite ends being vented. As i1- By suitable control mechanism uid under pressure lustrated in these figures yand in Figures 2 and 3, such Y 'i' in the same direction. Y

. fore, as shown in Figures 8, and 12, airwould be sup- Yfluid under presure is supplied to -the left` end of the port cylinder 55 and to the-'rightend of thestarboard cylinder cylinder 55 considered in relation to the directionA of'panel feed.` Y Q.' f QQ. ,7. f Q In Figure 2 air under pressure has been supplied .to the left end of` both small` cylinders 57, ktheright -ends being vented. Piston 58"offdrive frod, Slha's'thusfbeenrnoved fully to the rightlin 'itslcylinder 57, 'While the large piston 56 is held-fully in its position to the left, This has, caused the squaring arms 4 Yto'be moved inward sixinchesfrom Ytheir extendedYY positions. u

inches into engagement with the vedge ofthe thirty-six inch wide panel` P. As the port kpiston 56Y continues to move from Vits position of Figure 2 to its position of Figure 3, the squaring plates 42, pulled by their bars, Will drag the upper panel YP from' centered positionginto, the position oifset six inches from centered position which isshowninFigureS. n .Y Y V- Both the set of squaringplates 40 and theset of squaring plates v42 will' be stoppedin their positions, of Figure 3. The squaring plates 40 will beV stopped in the positions illustrated by bottoming of the starboard piston 56 at the left endrof its cylinder and of the small starboard piston 58 at theright end yof its cylinder 57. The 'positions of squaringrplates 42 will be established by the Vengagement of drive rod 54V with the hook 66 of its stop barY 64. Ylf it were not for such engagement, drive rod 54 would continue to move to the right beyond the position shown in Figure 3, because of the air pressure supplied to the left end of cylinder 57 tending 'toV move piston 58 to the right in such cylinder. This piston will remain fully ot the left in its cylinder, however, while piston 56 bottoms on the rightend of its cyl-inder`55, because of the much larger surface area of piston 56 on which the air pressure is acting; j p `The position of hook'66 ofY stopbar 64 engaged by drive rod 54 is shown in Figure l0, and in asimilar manner the stop mechanism is set byradjustment of handle A68 -to interrupt movement of the drive rodsin the proper positions for the width of Vthe panelsbeing fed and the type of feeding desired, i.e. whether centered or offset, in each instance. If the panels are to be fed-in centered position,

than the-other, -as shown in Figures 8, 10Vand 12,/fas Vdescribed'above. Adjustment Aof the stop bars 4will still 'be effected conjointly and to the sarne extent, as shown in these iigures.` Consequently,'thepositions of the hooks 66 and 67 will be set to be contacted Vby the one of the drive rodsrwhich moves farthest. The other drive rod will not be moved into engagement with its stop hook because iluid under pressure is notradmitted to the left end of the larger cylinder 55. Y y

When panels are to be fed in otset position, however, it is usually preferred thatalternate panels be oifset in oppositeV directions,although Vthe offsetting could always be For fone feeding operation, thereplied to the left'end of the large cylinder 55 for the drive rod 54 andto the rightiend 0f cylinder 55 foi-the drive jabutted respectively by the endsffofritheV 'one Side orf tiiebth'ef" from-its `central position, one drive rod will move farther ,20 by movement of` piston 56 acting on cylindert57, has drawn the squaring rodsr41 inwardly a distance, of,;twelve rod 51, the opposite-endsxbeingvented, for the purpose of fholdingthe starboard piston56 fully to the left as seen in .thoseii'gures lOn the next operation fluid under pressurelwould be supplied to the left end of the large cylinder 5 5 .for the drive rodV 51, so thatv piston 56 for that drive `'rodfwould be moved while simultaneously uid under "pressure",wouldr be supplied to the rightendofrtheY large cylinder 55 for'drive rod 54, thus preventing movement of `the piston 56 for drive rod 54.V In this instance, therefore,1the drive rod 51 would engage its stop hook 67, fwhereas drive rod 54 would be moved only an amount equal to.V the stroke of piston 5S in its cylinder 57. On ,the next operation the supplyof uid under presure would bereversed'again so'that drive rod 54 would make the .longer stroke and drive rod 51 would be moved only a relatively short distance, as shown in Figures 8, 10 and l2. V After the top panel of the stack has been squared in the desired position for feeding, as described above, motor 36'driving chains 34 moves a pusher bar 35 into engagement with a panel end to feed the panel. Motor 36 will have been regulated so as to feed the panel olf fthe stack as rapidly as the machine to whichV the panel is fed can accommodate it. In such feeding it is devrsirablevthat the bottomY of the panel beingV fed be Vdisposed in apredetermine'dA position relative to the machine j to which it is fed. The bottom' of the panel being fed should, for example, usually be precisely level with the table of the machine to which the panel is being fed or just slightly above it. The upper surface of the top panel 'on the s tack must, however, be below chains 34. Because the panels to be fed may range from one-quarter of an inch to two inches Vin thickness, it is Ydesirable to Vmake the position of the panel feed mechanism adjustable vertically to accommodate panels of diierent thicknesses.

As mentioned previously, the sheet feed mechanism upward movement ofthe sheetA feeding structure.

bars 31 are mounted for vertical movement on the swinging ends of arms30. To locate the bars 31 and the chains 34 at the proper elevation to accommodate panels of the thickness to be fed,.therefore, Vit is only necessary to limit the downward movement of the bars 31 Vat the proper position. Downwar'd movement of the bars is thus limited by chains 3'6 attached tothe bars 31 preferably at their vcentral portions, and' extending upward over a supporting shaftv 37 journaledV on the'upper portion of therframe Vsuperstructure 15. The rotative position of shaft 37v may bev altered by turning shaft 38 which 'is connected by chain and sprocket mechanism to shaft 37. Shaft 38 is turned by movement of handle 39 connected to it, and this handle may have a latch pin engageable in holes of the plate 39 to hold the chains `6 at the desired elevation selected.

It will be evident-that the chains 36 merely limit downward movement of bars 31. If the elevator should lift a stack of panels Vso that the upper panel engagesV and lifts chains 34 and Ythese bars, the chains 36 will not prevent lnstead, the arms 30 will simply be swung upward, and such `nfiovement will be cushioned by such upper panel assuming the weight'of the'superstructure. The arms 30 of one pair are formed-as bell cranks having lateral extensions 7. VToV Vthese extensions are connected tie members 70 extending into a casing 71 and-secured to a piston fitted in' thecasing. Y Air under pressure Vmay b'e supplied to the casing by a pipe 72, so that the weight of the superstructure on arms 30 will eEect compression of the air by the force on it of the piston in the casing 71. The pres- Usure of the air can be regulated with such a construction 'to balance` theV weight of the panelfeed and squaring mechanism. Y Alternatively, a plunger in the casing may Y engage a compression type spring above it, or a combina- 9 :stack :of vpanels supplied to fa tloeation adjacent-to the feeder before all the panelsjhavefbeencfed-ffrom theriext fprevious stack. :Sucha'fresh stack to be :fedlis show nfat the right of Figure 16 and in the backgroundfof Figure v1, which can be delivered by suitable conveying means to :the location illustrated. rhis panel staokshould'not be .Permitted to .move into registry Vwith theelevator until it is intheposition showninFigures 1 and 16. Itisdesirable, therefore, `tohold thestack in the position shown in Figures :1 and 16 untilthe elevator has descended fully.

'-I'he newtstackof panels may be delivered to the posi- ;tiongshown inl Figure l or 16 by a gravity conveyor, or by an impositive surface friction conveyor, as may be desired. ,To insure that .the stack does not progress-closer to the elevator than the .position shown, the idler roll V1 .at'the right of Figure 16 has brake means which ordinarily holds it against rotation and thereby deters further movement of the panel stack until Lsuch brake means are released and the rolls 1 driven positively. -Brakemeans suitable for this purpose are shown generally in Figure 1 and in detail in Figure V19, astincluding a brake housing s located at the end of lroll 1' on which the brakeis effective. i

The roll il with which the brakemechanism is associated is carried by a shaft 80 journaled in a pillow vblock 8.1. The end of this Vshaft projects beyond the pillow block and through the boreof a stationary-mounting@ to which the cylinder 8 is connected by threadsv83. Withinthe cylinder is received an kaxially slidable collar 84 encircling the end of shaft 80 and connected to it for conjoint rotation by a key 85. j

Between the collar l84 and the V.end 86 of cylinder 8 remote from the roll 1 is received a freely slidable piston 87. Fluid under pressure may be supplied to thecylinder between its end 86 and piston =87 through a conduit .83.

Such fluid could be either a compressed gas, such as cornt pressed air, or a liquid, such as oil under pressure.. In either case the pressure of the fluid will force piston 87 to the left as seen in Figure 19, so that it will press collar 84 against the face of mounting 82. The surfaces of these parts may be of material which, when thus engaged, will haveia high coefficient of friction. Shaft 80 willthus be eiectively connected to the stationary mountingSZ and consequently willbe held against rotation.

A principal purpose ofthe panel feeder described above isto' feed yindividual panels from a stack in automatic fashion. Consequently, a control panel 100 incorporates suitable relays and controls shown diagrammatically in Figure 20 which are coordinated with appropriately Vlocated control switches to edect'automatically the proper energization and deenergizationV of Vthe various components Vof the feeder. In effecting `automatic operation of thepanel feeder, however, it is important that such feed operation be eifected properly irrespective of variations in the height of panel stacks supplied to the feeder and irrespective of differences Vinjheight of various portions of such a stack.

A typical use of such a panel feeder is to feed `the sheets edgewise one at a time to a sanding machine. Prior V to such a sanding operation, therefore, the panels may be of nonuniform `thickness and, if one end of each panelis thicker than the other and all of the thicker ends are in overlying registry and all of the thinner ends are in `overlying registry, the height of one end of the stack may be appreciably more than the height of the other end of the stack. Under such circumstances it is not at all certain that the panel feed bars 35 shown in Figure l1, for example, would properly engage the edge of the uppermost panel, unless the top of the Ypanel stack were leveled so that the uppermost panel would be parallel tothe chains 34. Mechanism for effecting such operation is shown best in Figures 20 and 21.A

Each of the chains 28 connected to the elevator drive cylinder 24 isshown as being Alooped around a sprocket Q ,atfne end 4and a sprocket 9.0 at-the other end. One

oft-hase sprockets 9 'is 'keyed'to the 'shafti91iicarr5dng one vof-the gears 129, Yand -the other sprocket 9 'is-keyed to the shaft 92 vat the opposite fend of the superstructure. The sprockets 9, therefore, are the driving elements for the shafts 91-and 92, andthe sprockets J are merely idler or guide sprockets. If the chains 28 were ixedly connected to the 'cylinder 24 of the elevator drive mechanism, Vit will be evident that all of the chains 2 would be driven equally through the shafts 23 so that all portions of the elevator r17 would be raised equally. lIn order to compensate forpossibleV dierences in height of opposite ends of the stack, therefore, mechanism is provided to move the chains 2 at one end ofthe elevator relative tothe chains at the opposite end for the purpose of ltilting the elevator 17 to some extent.

While the opposite ends of one chain 28 are secured directly to the opposite heads of cylinder 24, the ends of the other chain may be connected to the opposite ends of a rod `93 adjustable lengthwise of this cylinder, Such. rod is slidable through apertures 94 in the opposite cyl-- inder heads of cylinder 24. In order that cylinder 24 may be effective to move the chain 28 in which rod 93? is connected, a thrust connection must be provided between such rod and the cylinder 24. Movement of rod 93 and its chain driving the chains 2. at one end of the elevator 17 relative to fthe other chain 28 and the chains 2 at the opposite end of the elevator 17 may be effected by making the 4thrust connection between the rod 93 and the cylinder 24 adjustable.

The adjustable thrust connection between rod 93 and cylinder 24 includes a small auxiliary cylinder 9S mounted directly onone ofthe heads of the cylinder 24. The rod 93 extends vthrough this cylinder and 'has fixed to it a'piston 96 fitted Vreciproc'ably in the cylinder 95 as shown in Figure 21. The length of the stroke of pistonV 96 inl cylinder 95 determines the amount of relative movement which can Vbe effected between the two chains 28, co-nsequently'between the chains 2 at the opposite ends of the elevator 17 and therefore the amount of tilt of which Vthe `elevator is capable for the purpose of leveling the uppermost panel of a stack.

Movement of piston 96 relative to cylinder 95 is effected by supply of iluidtundernpressure, such as oil, to one end or `theother of the cylinder through connections 97 and 98, respectively. vIt isV preferred that the relationship of chains 28 be established so that when Vthe piston 96 is located centrally of the cylinder 95 as Vshown in Figure 1 'the elevator platform 17 lwill `be level. By supplying `fluid under pressure through connection V97, therefore, to the left end of .cylinder 95, as seen in Figures 20 and 21,l the piston 96 will be moved to the Vright in such cylinder, so that the chains 2 at the right end of the velevator 17 as seen in Figures l and 2O will be raised to lift the corresponding end ofthe elevator. Qn the contrary, if fluid under pressure is supplied through connection'98 to Ythe right end of cylinder 95, `the piston 96v will be moved to the left, as seen in Figures 20 and 21, so that the chains 2 carrying the right end of the elevator 17 Vas seen in 'Figuresl and 20 will be lowered,

correspondingly lowering vthat end of the elevator.

Itis 4preferred that supply of pressure uidto one Vor the other of connections 97 and 98 be controlled automatically to effect a self-leveling operation of the top panel on a stack when .the elevator has raised such panel substantially into edge-feeding position. To effect control in this manner, control elements 99 and 99 `are located Vrespectively at opposite ends of the Vpanel superstructure which may be carried by a Vbar 13.1. Sensing element 99 may control :supply of fluid under pressure to conduit 97 to effect raising of the right end of the elevator V17 so that the corresponding end of the uppermost panel willengage sensing element 99. Conversely, sensing element 99 may control the supply of uid under-pressure to connection 98 so that, if this sensing element is engaged rst by the top panel of a stack, rod.:

Y 93 will be shifted by movement of ypiston 96 to lower *top panel engages the sensing element 99.

Y The location, function and operation of the various components of the automatic control mechanism can be correlated best Vin connection with a description of the feeder operation. Itwill be understood that various features of the electrical control mechanism may be varied in providing mechanism to produce a desired automatic operation of the apparatus.V The electrical control mechanism will be operatedrby a power supply 101 which may have a voltage higher than necessary for the operationof the control mechanism. Such powensupply is controlled by a master switch 102 and the voltage is reduced to the desired value by a transformer 103. Preferably'the output side of the transformer is ll() Volts Y and one or both of the legs of this circuit may incorporate fuses 104.

Assuming that the elevator has been emptied and has just descended to its lowermost position shown in Figure 1,'the elevator frame will have-engagedY and closed normallyopen switch 105. It'is assumed further that'an automatic operation of the feeder is desired so that the switch 106 is in the position shown in Figure 22 in engagement with the automatic operation terminal 107, as

distinguished from the manual operation terminal 108. Closing of thefswitch 105 effects energization of relay 109'controlling operation of the roll motor 110, which drives the rolls 1 and 11, and energization ofthe solenoid 111 which closes the normally open valve 112, preventing access or' air under pressure through conduit 88 to' the brake cylinder 8, thus releasing the brake of roll 1'. As soon asV the brake is released the action of gravlty Y will move the new stack of panelsV shown in Figures -1 and 16, causing roll 1 to turn. Alternatively, the stack may be thus moved by an impositive conveyor :on the feed side of roll 1'. When the leading edge of the stack ofY panels reaches the first roll 1, the stack will be moved on toward the elevator because such rolls will be kept moving by 1 continued energization of the motor 110 Ythrough relay 109, still energized by the elevator holding switch 105 closed. To this time closed switch 105 has also maintained solenoid 111 energized to lgeep brake 8 released by holding valve 112 closed.` J

Shortly after the trailing'edge of Vthe stack of panels is moved off roll 1', the-leading edge of the stack will engage normally closedswitch 113 and open it. Since this switch is in series with switch 105 in the circuit of solenoid 111, suchopening of switch 113 will deenergize solenoid 111, releasing valve 112 to move to its normally open Vposition so that again air pressure is admitted to the brake mechanism. The brake will thusbe applied to 1 roll 1"so 'that it will hold theV next stack Soi panels Vout of contact'with the first roll 1 until the brakeV is Vreleased again. As'the elevator israised, switch 105 vwill be released to break the circuit .to solenoid 111 before the stack of panels. is-raised ol switch 113, allowing it to open again. The brake releasing solenoid 11,1v thus .re-

Vmains deenergized to keep the brake applied until the Vposition andY Yswitches 116 andV 117 are releasedafter the stack S 'has been'pla'ced as desired, the final effect will be toi-locate the stack of panels over the elevator 16 with the-rolls ll'stopped so that the panel'stack Ywill stay insuch position. Thereafter, the elevator 16 vwill be raisedY to lift the stack of panelsfrom the vrolls 11, and again the elevator may be controlled either automatically by placing switch 119 in engagement with contact 120, as shown in Figure 20, or manually by moving such switch into engagement with contact 121.

If the operation is to be of automatic character, switch engaged with Aits left contact in Figure 22 bythe stack of panels engaged with it, opposite to its normal position, will energize relay 122 to elect energization of thesolenoid of solenoid valve 123, which will open conduit 27 for supplying iluid under pressure to the right end of cylinder 24, as seen in Figures l and 20, while venting theconduit 26. Even though switch'115 should be closed only momentarily, relay 122 will remain energized through its holding circuit so thatthe upward movement 'of the elevator will be continued until `the upper panel of the stack S engages and lifts the sensing e1ement'124.v Upward movement of such sensingY element will effect opening of switch 125, normallyV closed, to interrupt the circuit through the'solenoid valve 123. Relay 122 will, however, remain energized, even when switch 125 is opened. Y Y

As the sensing element 124 is moved upward, not only is upward movement of the. elevator interrupted by opening of switch 125, but the sensing element also closes switch 126 to energize relay 127. Energization of such relay initiates operation 50i motor 128 which drivesthe chains 34 carrying. Vthe ,feed bars 35 engageable with the end of the top sheeton the stack S to be fed from the feeder. Relay 127 also is providedrwith aiholding circuit so that this relay will continue to be energized even after switch 126 is opened. Motor 128 'may be an electrically controlled fluid motor.V

A further action effected by raising of the sensing element 124 by the top sheetof the stack is theclosing of switch 130 which initiates the squaring operation 'elected' by movement of the squaring armsV 4 and 41., Y' Thethree4 operations of termination of the elevator raising movement by opening of switch 125, starting of the -feed motor :by closing of switch126, and initiation of theV squaring arm movementV by closingv of switch 130 all occur vVsubstantially simultaneously. g

Closing of switch 130 to initiate the squaring arm movement will always energize the solenoids of valves 131 and 132 controlling the ow of iluid Vunder pressure to the left ends of the starboard and port smaller cylinders 57 through conduits 57". In addition,v closing of this switch will'admit fluid under pressure to one ,end or the otherofthe largelsquaring arm operating cylinders depending upon the particular type of desiredV squaring operation selected in` advance by the operator.

kIn order to select the type of squaring operation desired, a selector switch 133 isr provided which can be set to engage any one ofthe contacts 134, .135, 136 and 137. If, as shown in Figure 20, the switch arm 133 isy in contact with switch point 134 when the squaring switch switch 106 maybe moved to engage contact 108, where- Y.

upon by closing and holding switch 116 the panel stack may be moved still farther, or by closing switch 117 the motor driving rolls 1Y and 11 may be reversed to withdraw the panel sack outward somewhat. For safetyl purposes an overload circuit breaker 118 may be incor-V porated Yin the circuit of roll motor 110.

left as seen in Figures 2 and 3.

130 is closed, relay 138 will be energized, which in turn vw'll energize theV solenoid of valve 139. This valve normally would be in ajposition Vsuch that luid under pressure would be supplied to the right endY of the large port cylinder 5S so as to hold its piston 56 fully to the Upon energization of this solenoid, however, the valve would be moved to supply fluid -under pressure through conduit 55 to the left end ofV the large port cylinder, 'so that the piston-S6 would -be moved to'the right in the ,manner shown in Figures 2.V and 3 until the end of squaring rod 54 engages lplates 40 in a predetermined position, as shown in Figures 2 and 3, irrespective or" the degree of movement of the large port piston 56 alone, or, in addition, the movement of the small port piston. Whatever the width of vthe panel being squared, therefore, plates 42 on squaring arms 41 will shift the panel until its opposite edge is engaged with the plates 40 to locate such opposite edge relative to the machine to which the panel is fed.

If the switch yarm 133 were in contact with the switch point 135, relay 141 would be energized, which would effect energization of the solenoids of both valves 139 and 140, so that air under pressure would be supplied to the left ends of lboth large cylinders 55 through the conduits 55. With such setting of the valves both large pistons would move to theright as shown in Figures 7, 9, ll, 13, 14 and 15, until their respective rods 51 and 54 had engaged their respective stop hooks 66 and67. In each instance, therefore, the panel to be fed would be squared in a central position.

If the selector switch 133 Ywere placed in contact with the switch point 136, closing of squaring switch 130 would energize relay 142. Such energization would cause energization of the solenoid of only valve 140, so that, opposite to the illustration of Figures 6, 8, l and 12, air under pressure would be admitted to the left end of only the starboard cylinder 55, causing its p-iston 56 to move while the piston 56 of the port large cylinder would be held to the extreme left end of its cylinder. Consequently, upon each feeding operation the top panel would be squared in an offset position, always toward the starboard side of the feeder. irrespective of the width of the panel being fed, the location of the starboard edge will always be the same, established by the location of plates 42.

If the selector switch arm 133 is in engagement with switch point 137, closing of switch 130 will energize one or the other of relays 143 and 144, depending upon the rotativevposition of stepping switch wheel 145. Each time theswitch 130 is closed when the selector switch arm is in such position, the solenoid 146 of suchstepping switch wheel will be energized to reciprocate the ratchet arm 147 to turn the switch wheel 145 one tooth. Current issupplied by a lead 148 to the center of this wheel, which carries the distributor strip 149. When in the position shown in Figure 20, the strip 149 would energize the brush 150 for transmitting current to relay 143. The next time that switch 130 is closed when switch arm 133 is in engagement with switch point 137 the ratchet mechanism 146, 147 would turn the switch wheel 145 through a quarter-turn, so that the strip 149 would be engaged by the brush 151, which is connected to relay 144. Immediately, therefore, this relay would be energized ,to yswing the relay contact arm 1,52 toward the coil of relay 144.

The switch point adjacent to relay coil 143, which is engaged by the relay switch arm 152, is connected to the solenoid of valve 139 controlling the supply of uid under pressure for shifting the large Vport piston 56 to the right as seen in Figures 2 and 3. The switch point adjacent torelay coil 144 engageable by relay Switch arm 152, on the contrary, is in circuit with the solenoid of valve 140, which controls the supply of uid under pressure to move large piston 56 of the starboard cylinder to the right. It

will be evident, therefore, that as long as selector switch arm 133 is in engagement with switch point 137 the rotary switch 145 will energize brush 150 and relay 143 in one instance and brush 151 and relay 144 in the other instance, alternately. Switch arm 152 by such relay energization will be swung from its position to lenergize the solenoid of valve 139 to its position to energize the solenoid of valve 140 and back again alternately.

With the stops 66 and 67 forthe squaring rods 54 ar1fd v51, respectively, set in onepfthe-positionsShown'in Figures 8, l()A and l2, for example, it will be evident that one squaring rod will engage its stop and then the other squaring rod will engage its stop in alternate operations.

Consequently, panels fed by the feeding apparatus will jbe squared -in offset positions, one sheet being oiset to one side, and the next sheet being offset to the opposite sidefalternately in successive operations; In each instance, of course, with whatever switch terminal the switch arm may be engaged, closing of squaring switch 130 will cause the solenoids of both valves 131 and 132 controlling supply of fluid to both smaller cylinders 57 to be operated for supplying uid under pressure to the left ends of such cylinders. The pistons 58 will not always move in their cylinders, however, for the reasons discussed in connection with the operation of the mechanism as portrayed in Figures 8, l() and l2.

The squaring arms 4 and 41 will remain in their inward squaring positions throughout the operation of feeding the top panel from the stack, because the top panel being fed will hold the sensing member 124 in its upper position until after the panel has been fed out from under suchvsensingmember, as shown in Figure 17. As the sensingYV member drops downward, the switch 130 will open, which will deenergize all of the solenoids of valves 131, 132, 139 Vand 140 which may have been energized, causing all the valves to be positioned for supplying air under pressure to the right ends of both the large cylinders 55 and the small cylinders 57. Consequently, both pistons 56 and both pistons 58 will be held fully to the left in their positions shown in Figure 4. The squaring arms will thereby be shifted outward to their position of greatest spacing.

Considerably before the panel reaches its position shown in Figure 17 the panel P will have been gripped by the machine to which it is being fed so that it will be pulled the remainder of the distance olf the stack of panels S without reliance upon the pushing action of a feed bar 35. In fact, if the feed bar continued to be engaged with the panel end during its movement by chains 34 around the arcs of sprockets 33 adjacent to the discharge end of the feeding mechanism, the bar 35 would scrape transversely of the panel edge, which might deface such edge or catch and tend to raise the trailing edge of the panel, which would be undesirable. Consequently, control mechanism is provided for interrupting the operation of the feed motor 128 briey when the feeding bar 35 approaches the sprockets 33 adjacent to the discharge endV of the feeding apparatus to enable the panel-pulling mechanism to move the panels trailing edge out of proximity tothe bar 35, so that no contact of the bar with the panel can occur yas such bar is moved upward around the sprockets 33 adjacent to the discharge end of the apparatus by the chains 34.

The control mechanism provided' to interrupt operation of feed motor 128 briey for the purposev discussed includes the switch 153, cwhich would be located conveniently to be closed by movement of a bar 35. Closing of such witch will energize relay 154 to attract simultaneously its switch arms 155 and 156. Such movement of switch arm 155 immediately will break the circuitrto the feed motor 128 so that it will stop hut without deenergizing the principal control relay 127 for thisA motor, which will remain energized because of its holding circuit. The simultaneous movement of switch armv156 will effect immediate deenergizatio-n of relay 154 so that the switch arms and 156 will tend to return to their relay-deenergized positions. arm 155, however, is a dashpot 157 which willdelay reclosing of this switch sufficiently so that the panel Pv may be removed to withdraw its trailing edge out of the upwardly moving path of the pusher bar 35.

When switch arm 155 recloses following -deenergization of relay 154, the feed motor 128 .will be reenergized Associated with the switch chain cycle.V n

dailies until after the chains 34- have been moved through an 'appreciable distance after switch 15S has again closed,

relay 154 will not be reenergized immediately because its switch arm 156 in its circuit is also provided with a dashpot 15S. This dashpot is shown as being longer or in some way slower acting than dashpot 157, so that reclosing of switch -156 will be delayed until switch 155 has reclosed and the chains 34 have been moved far enough 'to enable switch 153 to open. Relay )l5- will therefore not be reenergized until switch 153 has been closed again, which ywill be on the next panel feeding cycle.

When thus reenergized by reclosing or" switch 155, the

c feed motor 128 will continue to operate until the pusher bars'35 have almost reached positions at the extreme ends of the paths of chains 34. At this time the pusher bars `or chains will move switch 159 to open position, which Y will break the circuit of motor 12S and the holding cir- P in the stack S before the chains 34 have completed their movement into the position shown in that ligure. Nevertheless, because of the holding circuit of relay 1,27, such feeding operation will be completed even though-switch 126 has been releasedand'has been moved to open posi- Ytion by dropping of` the sensing member. Also, because of the downward movement of the sensing member, the squaring arm control switch 13u may' have opened to Y deenergize thesolenoids of thevarious valves 131, 132,

139 and 140 to elect retraction of the squaring arms into the position shown in Figure 16. In that event switch 125 also will have been released to close, which, because of the continued-energization of relay 122 through its holding circuit, would tend to reenergize the solenoid of valve 123 and cause the elevator 16 to be moved upward by supplying iuidA under pressure to theright end of cylinder VV24 through conduit 27.

Y Despite the closing of Vswitch 125, howeverVr upward movement of'the elevator will not occur until afterV the chains 34 havev completed'their movement to their initial positions with the crossbars 35 at Vthe extreme ends as shownj in Figure 17. .By this time, of course', switch l130 willhave been released'so that the squaring Varms have been retracted. Such sequence of operation is insured by the provision Vof switch arm 166 under the control fof relay 127. This switch, whichis normally closed, is in series withV switch 125 under the control of the sensing element124 and cannot return to closed position' until relay V127 hasrbeen deenergized, which is elected by opening of switch 159. Consequently, even though switch 125 land achain 34er bar 31 to 'raise the feeding mechanism supported on arms 3e 'without the sensing element being lited relative to such arms. For l.suchevent anV upper safety limit switchy 161 is provided which would'rbeactuated by excessive swinging movement of an arm or excessive upward movement of a bar 31, for example. Such safety switch is arranged in circuit with both elevator raising solenoid 123 and elevator lowering solenoid 162. As long as switch 161 is in engagementwith its contact 163 and switch 125 is closed, solenoid 123 will remain energized to continue upward movement of the elevator. Upon actuation of switch v161 to disengage its terminal 163 and engage its'terminal 163@ however, the circuit to solenoid 123'would be broken and instead a circuit would be completed -to the elevator lowering valve solenoid 162 controlling supply of liquid under pressure to Vconduit 26 supplying the left end of cylinder 24, ,as

seen in Figure l. At 'the same time supply of iluid under pressure to conduit 27 would-be discontinued. Consequently, the elevator immediately would move down and such downward movement would-continue until switch 161 had been released, whereupon it would be reengaged with its terminal 163. lf the dillic'ulty had been remedied has been closed, rela'y 127 must have been deenergized Y i at the completion of travel of chains 34 before upward movement'of the elevator is resumed. As soon as the elevator has moved upward the thickness of one panel, switch 125 will be opened again to interrupt its movement, and switch 126 will have been closed again to energize `relay 127 and open switch 166, so thatV the next feed operation of Vchains 34 willbe initiated andthe elevator again conclusion of suchY feedV will remain quiescent until the would Vcontinue to move upward andV cause damage to the machine if a safety switch were not provided.; Thus.

lfor example, a stick might be vincorporated in'a stack of p anels which would engage between the upper panel by that time, switch would be actuated to terminate theupward movement of the elevator, but otherwise if the elevator were raised suiciently again to move switch 161 out of contact with its terminal 163 and intocontact with its vterminal 163', the upward movement of the elevator again would be arrestedV by the actuation of this switch and it would be moved downward. Such short up and down hunting movement of the elevator would continue until the cause for such upward. overtravel of the elevator had been removed.

YWhen operating normally switch 125 would be closed andV Vopened-alternately to elect raising movement of the elevator 16 by increments equal to theY thickness of panels on the stack S until the last panel had been fed from the elevator. At that time, instead of the sensing element 124 being supported-in the intermediate position shown in Figure 17 by the next panel to beied, it would have dropped downward into the position shown in Figure l to close switch 164. Closing of such switch energizes relay 165, which breaks the holding circuit of elevator raising relay 122 and, by closing switchY 166, energizes the solenoid 162 of the elevator lowering valve to supply iluid under pressureV to conduit 26, whilepinterrupting supply of such fluid to conduit 27 Such supply of fluid will effect movement of cylinder '24 to the left, which drives chains 2 to lower the elevator 16, `17-into the position shown in Figure l. When the elevator reaches thisl position, normally closed switch k167 will be opened to deenergize relay 165 for interrupting downward movement of the elevator. g Y Y' As ralso explained previously, assuming `that another stack of panels S is in the position shown in Figures l and 16 to be fed to the elevator, the closing of switch 105 would have initiated movement of such stack of panels toward the elevator'. In theV absence of yinterference by the operator such stacky of panels rwill be fed automatically to the elevator, whereupon the elevator Vautomatically will be raised until the top panel of the new stack again reaches the feeding position. Thereupon automatic feeding of the panels from that stack will be elected in the manner described.

In some instances, it may be Vdesirable to lower the elevator before all the panels have been fed from the stack on it.V1 Alternatively it may beV desired to raiseV or lower the elevator'at will for some reason. For that purpose switch 119 may be swung from engagementwith switch point'12l) into engagement with switch point 121, and whenit is in the latter position the elevator control relays 122 and 165 cannotbe energized. vThe solenoid of valve switchfis momentary contact type, so that as soon as mthe operatorfs handisremoved from it, it will open ailtoma'ticallyfand v terminate upward movementl of the elevator. `Qonvfeljselry,Y the elevator may be moved down at willby closing of manual switch 169 to energize the solenoidvalv'e1'62. Again, this switch should be of the momentary'contact type, so that as soon as it is released by theoperator it will open.

In case of emergency, of course, the master switch 102 canbehpulledLwhereupon all of the drive mechanisms will be deenergized and movement of all parts of the feeder will stop.

As has beendisussed previously, it m'ay be desirable to incorporatein the mechanism an Varrangement to modify the action of `tlle v,main Yelevator hoisting drive by tilting the elevator somewhat toV compensate for difference in thicknesslof a Vstack ,of panels at its opposite ends. The auxiliary adjustingmechanism to move relatively the chains 2 at vopposite endsof the elevator has been described mechanicallyinvconnection with Figures 20 and 21. The sensing elements 99 and 99 at opposite ends of the elevator, which would be engaged by the opposite ends of the top panel on astack, are arranged to control respectivelyswitches 170 and 171. These switches can energize respectively solenoids 172 and 173 of valves to control the supply of uid under pressure to conduits 97 and 98 connected to the left and right ends, respectively, of auxiliary cylinder 95.

As the elevator is raised, if switch 170 is engaged lirst, indicating that the left end of the stack of panels as seen in Figure 2O is higher, liquid would be supplied to the conduit 97 by the valve actuated by energization of solenoid 172 corresponding to switch 170. The valve controlled by solenoid 173, which is not energized, would be positioned to connect conduit 98 communicating with the right end of cylinder 95 to a hydraulic liquid return conduit. Consequently, the piston 96 would move to the right, as seen in Figures 20 and 21, to raise the right end of the elevator more than the left end. As soon as the right end of the top panel engaged the sensing parallelogram 99 to move switch 171, its normally closed upper contact would be broken, thereby deenergizing the valve controlled by solenoid 172 so that no more pressure uid would be supplied through conduit 97 to the left end of cylinder 95. While movement of the switch arm into engagement with the opposite contact would seek to energize solenoid 173 for supplying fluid under pressure to the right end of auxiliary cylinder 95, such solenoid would not be energized because its circuit would be broken by switch 170. This switch also has a coutact which would be closed in the circuit of solenoid 173 when the sensing parallelogram 99 is not engaged by the top panel of a stack. With both of the sensing parallelograms 99 and 99' engaged, however, both solenoids 172 and 173 would be deenergzed so that the piston 96 would not be shifted additionally in its cylinder 95.

Piston 96 would therefore remain stationary relative to its cylinder 95, despite continued movement of cylinder 24 relative to the stationary rod 25, until the stack of panels had been raised suiciently to open either switch 125 or to move switch 161 out of engagement with its contact 163. In either event solenoid 123 would be deenergized to cut olf the supply of uid under pressure to cylinder 24 so that upward movement of the elevator would be terminated. While the movement of piston 96 in its cylinder 95 normally will occur during continued upward movement of the elevator effected by the cylinder 24, it is important that the leveling adjustment elfected by piston 96, as well as the upward movement of the elevator, be interrupted if .movement of the feed bars 35 should begin. The current supply to the solenoids 172 and 173, therefore, like that to the solenoid 123 controlling the upward movement of the elevator effected by cylinder 24, is through the switch 160 of relay 127. If

Y .M are.. this relay should be energize to openjthisswitch, the circuit including solenoids 172 and 173 would deenergized simultaneously.l A,

As has been Ydescribed previously, the next operation is for the feed mechanism to,slide off Vthe stack the top panel, which has been squaredand shifted, if necessary, into proper alignment with the predetermined feed path.. Pressure uid is not admittedagain toeither conduit y97 or 98, however, to shift piston 96 relative to its ,cylinder until solenoid 123 has again been energized to index` the elevator upward a distance equal to the thickness of the new top panel o n thewstack. V.'lf'hereupondoiie or the. other of switches and,17,1 will bemoved first, and then both together, as maybe required to level the -new toppanel. C Y, .I

While, becausey of cumulative variation in thickness of the panels'in a stack, the movementof piston 91E-felative to cylinder 95 might be 'considerable when the switches 170 and 171`are actuated by the fu'st top panel of a new stack, the piston 96 byactuation of such switches will be`V returned gradually towardits central position in cylinder 95 by increments as the, height of the panel stack decreases because successive 'panels are removed from it'. When the last panel in the 'stack is leveled by movement of piston 96 relative to cylinder 95',`therefore, the .piston will be approximately in its 'central' position, so 'that the elevator will be suiciently level to receive the next stackV of panels when -it has descended to its bottom position. The arms 99 and 99 of the parallel linkage sensing de- Vices will be long enough so as to be engaged by the opposite ends of the top panel of a stack in each instance whether such panel be long or short within the range of panel lengths intended to be fed by the sheet feeder.

I claim `as my invention:

l. Panel hoisting mechanism comprising an elevator platform, hoisting chain means supporting said elevator platform and operable to move it upwardly, two shafts disposed in spaced, parallel relationship and connected to drive said chain means, a stationary piston and piston rod, a cylinder housing said piston and shiftable relative to said piston rod, and drive means interconnecting said cylinder and each of said shafts, operable by said cylinder reciprocating along said rod to effect conjoint rotation of said shafts for driving said hoisting chains to raise said elevator platform.

2. 'Ihe panel hoisting mechanism defined in claim l, in which the drive means includes a connection between the cylinder and one of the shafts, and power means operable to effect movement of said connection to alter the relationship between the cylinder and one of the shafts without Ichanging the relationship of such cylinder and the other of the shafts, for driving the hoisting chain means to tilt the elevator platform.

3. In a panel handling device having feeding means operable at a predetermined level to feed panels from a stack of panels, hoisting and control mechanism comprising elevator means operable to receive and lift a stack of panels to dispose the top panel of such stack at such predetermined level, sensing means engageable by such top panel moving upward to such predetermined level, control means operable automatically by said sensing means moved by such top panel to terminate upward movement of said elevator means, supporting means constituting a `common support for said sensing means and for the feeding means, and adjusting means operable to alter the elevation of said supporting means for shifting simultaneously the location of said sensing means and the feeding means, and means automatically operable by removal of such top panel from the stack by the feeding means to effect resumption of upward movement of said elevator means.

4. The panel handling mechanism defined in claim 3, in which the supporting means includes a framework, parallel linkage supporting said framework, and means Ysaid parallel"linkage. Y' f .5. 1 The panel handling mechanism defined in claim 4,

operable to limit the degreero/f 'downward swingingvof in which the'parallel link age includes a bell crank and resilient means cushioning swinging of said bell crank.

6. In panel handling mechanism, means operable to transport a stack of panels edgewise including a roller located in the path of a stack of panels transported by said means, a stationary housing adjacent to one end of said roller, a rotative member received within said housing and rotatably connected to saidroller, said rotative member being movable -into frictional engagement with said housing, and actuator means movable to effect frictional engagement between said rotative member and said housing to restrain rotationof 'said roller.

7. Panel hoisting mechanism Vcomprising an elevator platform, two spaced lifting meansV engaging said elevator platform at generally horizontally spaced locations, drive means drivingly connected to both of said spaced lifting means for driving them simultaneouslyto lift said platform, 'and piston-and-cylinder means interengaged between Ysaid drive means and one of said liftingrmeans and operable by relative movement of the piston and cylinder of said piston-and-cylinder means to move such one of said lifting means relative to said drive means to tilt said elevator platform.

8. Panel hoisting mechanism comprising an elevator platform, two spacedY lifting means engaging ,saidY elevator platform at generally horizontally spacedlocations, and drive means includingfa'pistonand piston rod component, a cylinder component ho'sing'lthef piston of` piston and piston rod component, means mounting one of said com- Vponents',stationaily, and means drivingly connecting the other of said components to bothV of saidspaced lifting means for driving them simultaneouslyto lift said platform by relative movement of said two components.

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